RATE OF LEAF ELONGATION AS AFFECTED BY THE INTENSITY OF THE TOTAL SOIL MOISTURE STRESS

Abstract

Rate of leaf elongation on cotton plants was ascertained with respect to increasing intensity of the soil moisture stress. Leaf elongation virtually ceased at the higher intensities of induced stress and resumed on alleviation of the stress by irrigation. During a given irrigation cycle, elongation was expressed empirically as a 2d degree function of soil moisture stress. This functional relationship was characterized by an approach to a maximum at the theoretical time at which growth ceased. Since the derivative becomes zero at a maximum, this value is used in solving the differentiated equations for the intensity of soil moisture stress limiting to leaf elongation by using the empirically derived constants for the functional relationship between leaf length and moisture stress. This procedure gave values consistently close to 15 atm. for the moisture stress inducing leaf-growth cessation for different irrigation cycles during the growth of a given leaf, for different leaves on the same plant, and for leaves on different plants.